This application is aimed at elucidation of certain conformational and mechanistic aspects of the gonadotropins, human choriogonadotropin and lutropin. The Physicochemical studies will include electron paramagnetic resonance, nuclear magnetic resonance and circular dichroism. The mechanistic studies will be directed mainly toward actions in Leydig tumor cells; these studies include the role of gonadotropin carbohydrate in eliciting a biological response, characterization of gonadotropin induced proteins, actions of estrogen and the action of a putative lutropin variant in kidneys. Physicochemical studies will be conducted on beta-endorphin and derived peptides, and the epsilon opiate receptor, which exhibits beta-endorphin specificity, will be characterized. Lastly, the regulation of pro-opiomelanocortin will be studied in transformed Leydig cells.